The invention relates to a dispenser. Particularly for flowable media which may be gaseous, powdery, pasty and/or liquid. The dispenser is held and operated single-handedly to discharge the medium. The dispenser is intended for use in various positions. For example with the outlet located downwards or upwards. A valve assembly or valve unit is provided. It responds to changes in position of the dispenser by differing valve states.
Such valve units may be an outlet valve, vent valve, mixing valve or the like. The valve unit can control the delivery, pressure or pump chamber. When an inlet valve the volumetrically variable pressure chamber can be filled with medium from a reservoir and through this valve while being expanded or evacuated. The flow direction is then oriented substantially parallel to the pump or valve axis or the like. The valve unit comprises two valves or valve bodies and valve seats following in the flow direction. The upstream valve body is to be translated into its closed position only by gravity. The downstream valve body located nearer to the pressure chamber is translated into its closed position by overpressure in that chamber. An arrangement of valves or valve bodies inverse to the latter is also conceivable.
It may be a disadvantage with such dispensers that the valve responds blocked or delayed when in an end position, for example the closed position. The valve body is thereby pulled into its seat by vacuum or the like so that even higher vacuum at the other side is not instantly sufficient to unseat it. This happens particulary with the first valve which closes as a pop or back valve upon the overpressure in the hauling chamber and should instantly open for filling when this chamber is evacuated. This can also concern the second valve.